1. Field of the Invention
The present invention is directed towards window locks, and particularly toward manual handles for actuating window locks. Specifically, the present invention is directed to a flush mount or low profile actuating window lock for casement windows. More specifically, the present invention is directed to a flush mounted lock actuator designed to drive a lock bar that locks and unlocks a casement window, and protrudes from the window frame significantly less than prior art designs while employing linkage to prevent the actuator from being back driven from either the locked position or unlocked position. The present invention introduces a lifter and a restrictor arm that shift the pivot points of the handle. The lifter moves vertically relative to a horizontally driving fork component helping to achieve a low profile actuation of the lock.
2. Description of Related Art
Generally, a casement window is a window unit in which the single vent cranks outward, to the right or left. Casement windows are hinged at the side. (Windows hinged at the top are referred to as awning windows.) They are used singly or in pairs within a common frame. Casement windows are often held open using a casement stay. Casement windows open like doors. Like doors, either the left or right side is hinged (or, more accurately, pivoted), and the non-hinged side locks securely into place by a lock bar driven by a lock handle. Unlike a door, the casement window opens not by a knob or handle but by means of some variation of a gear driven operator or lever, which is placed around hand height or at the bottom. A gear driven operator, stay, or friction hinge controls the position of the sash is necessary when the window opens outward, to hold the window in position during inclement weather, such as high winds.
The locking system for a casement window is typically on the side of the window. Lock handles for casement windows are known in the art. Generally, a lock handle is mounted on the frame of the casement window and moves an internally mounted fork component left or right. The fork component drives a lock or tie bar that is also mounted to the frame. One type of locking mechanism for a casement window uses a flat tie bar slidably mounted to the window frame along the open side of the window. The tie bar is provided with multiple pins for locking and driving that extend perpendicularly outward from the tie bar. A locking handle is provided on the interior of the window frame that can be thrown by the user between locked and unlocked positions. The locking handle slides the tie bar, which moves each locking pin between a corresponding locked and unlocked position. A typical lock bar and lock handle to drive the lock bar is shown in U.S. Pat. No. 7,946,633, entitled “Low Friction Adjustable Roller Pin,” issued to Minter on May 24, 2011.
Lock handles of the prior art are known to protrude from the casement window frame at a distance of approximately 20-25 mm. This protrusion is due to the internal driving mechanism within the handle. Casement window lock handles of the prior art drive a fork component, which engages and slides the lock bar. In order to drive the fork component from one side to the other, the handle casing must have sufficient depth to allow for the handle to pivot about the casing and to allow the fork internally to shift from side to side.
The most relevant prior art does not teach or disclose a locking mechanism capable of low profile (on the order of 8 mm) flush mounting that can be adapted to work with existing tie bar locking designs. For example, in U.S. Pat. No. 5,087,087 issued to Vetter, et al., on Feb. 11, 1992, entitled “Sash Lock,” a basic multipoint window lock mechanism is taught using an actuating lever/handle that drives a sliding lock bar. The actuating lever handle has a pin located at the opposite end from the handle end. The pin is engaged in and drives a fork component on the lock bar. This prior art does not disclose, describe, or suggest any type of lifter mechanism in combination with the fork component to achieve a significantly reduced profile lock actuation. Nor does this prior art design introduce additional linkage to prevent back driving the lock.
In U.S. Pat. No. 5,813,710 issued to Anderson on Sep. 29, 1998, entitled “Flush Lock Actuator,” a lock actuator is disclosed to provide a “flush” lock appearance. However, for reasons discussed further herein, the low profile feature of this invention is provided with a design distinctly different from the present design. The Anderson design teaches a handle that is symmetrical and flush with the body of the actuator. The handle is pivoted with respect to the casing about its center on a pin. One end of the handle pivots towards (and into) the window frame, while the other end pivots out of the body and away from the frame. The end that pivots into the window has an actuating link attached to it that drives the lock bar. There is no “lifter” as taught by the present invention to work in combination with a fork component to reduce the casing profile, nor a restrictor arm for redirecting the pivot points of the handle, nor is there any linkage or over center action to prevent back driving the lock.
In U.S. Pat. No. 5,829,802 issued to Anderson, et al., on Nov. 3, 1998, entitled “Multi-Point Lock Operator For Casement Window,” a lock actuator is disclosed that drives a multipoint lock bar. Although the actuator handle is not flush, the handle swings a full 180° so that it lies flat at both the locked and unlocked limits of motion. The far end of the actuator handle drives a “universal” link that is connected to the lock bar. In this design, the handle is pivoted directly on the casing or body of the device, which is distinctly different than the present design. Consequently, there is no need for a restrictor arm or any additional linkage for over center security to prevent the lock handle from being back driven.
In general, the prior art is silent with respect to salient features of the present invention that achieve flush mounting and prevent back driving the lock.